Rapid Detection Of Isoniazid Resistance Research Articles

Treatment With a Three-Drug Regimen for Pulmonary Tuberculosis Based on Rapid Molecular Detection of Isoniazid Resistance: A Noninferiority Randomized Trial (FAST-TB).

BackgroundThe rationale behind the use of ethambutol in the standard tuberculosis treatment is to prevent the emergence of resistance to rifampicin in case of primary resistance to isoniazid. We evaluated whether early detection of isoniazid resistance using molecular testing allows the use an ethambutol-free regimen.MethodsFAST-TB, a phase 4, French, multicenter, open-label, non-inferiority trial, compared 2 strategies: (1) polymerase chain reaction (PCR)-based detection of isoniazid and rifampicin resistance at baseline using Genotype MTBDRplus version 2.0 followed by ethambutol discontinuation if no resistance was detected (PCR arm) and (2) a standard 4-drug combination, pending phenotypic drug-susceptibility results (C arm). Adult patients with smear-positive pulmonary tuberculosis were enrolled. The primary endpoint was the proportion of patients with treatment success defined as bacteriological or clinical cure at the end of treatment. A non-inferiority margin of 10% was used.ResultsTwo hundred three patients were randomized, 104 in the PCR arm and 99 in the C arm: 26.6% were female, median age was 37 (interquartile range, 28–51) years, 72.4% were born in Africa, and 5.4% were infected with human immunodeficiency virus. Chest x-ray showed cavities in 64.5% of the cases. Overall, 169 patients met criteria of treatment success: 87 of 104 (83.7%) in the PCR arm and 82 of 99 (82.8%) in the C arm with a difference of +0.8% (90% confidence interval, −7.9 to 9.6), meeting the noninferiority criteria in the intention-to-treat population (P = .02).ConclusionsIn a setting with low prevalence of primary isoniazid resistance, a 3-drug combination with isoniazid, rifampicin, and pyrazinamide, based on rapid detection of isoniazid resistance using molecular testing, was noninferior to starting the recommended 4-drug regimen.

Rapid detection of isoniazid resistance in Mycobacterium tuberculosis isolates by use of real-time-PCR-based melting curve analysis.

The MeltPro TB/INH assay, recently approved by the Chinese Food and Drug Administration, is a closed-tube, dual-color, melting curve analysis-based, real-time PCR test specially designed to detect 30 isoniazid (INH) resistance mutations in katG position 315 (katG 315), the inhA promoter (positions -17 to -8), inhA position 94, and the ahpC promoter (positions -44 to -30 and -15 to 3) of Mycobacterium tuberculosis. Here we evaluated both the analytical performance and clinical performance of this assay. Analytical studies with corresponding panels demonstrated that the accuracy for detection of different mutation types (10 wild-type samples and 12 mutant type samples), the limit of detection (2×10(3) to 2×10(4) bacilli/ml), reproducibility (standard deviation [SD], <0.4°C), and the lowest heteroresistance level (40%) all met the parameters preset by the kit. The assay could be run on five types of real-time PCR machines, with the shortest running time (105 min) obtained with the LightCycler 480 II. Clinical studies enrolled 1,096 clinical isolates collected from three geographically different tuberculosis centers, including 437 INH-resistant isolates and 659 INH-susceptible isolates characterized by traditional drug susceptibility testing on Löwenstein-Jensen solid medium. The clinical sensitivity and specificity of the MeltPro TB/INH assay were 90.8% and 96.4%, respectively. DNA sequencing analysis showed that, except for the 5 mutants outside the detection range of the MeltPro assay, a concordance rate between the two methods of 99.1% (457/461) was obtained. Among the 26 mutation types detected, katG S315T (AGC→ACC), inhA -15C→T, katG S315N (AGC→AAC), and ahpC promoter -10C→T accounted for more than 90%. Overall, the MeltPro TB/INH assay represents a reliable and rapid tool for the detection of INH resistance in clinical isolates.

Meta-analysis of pyrosequencing for the rapid detection of isoniazid-resistance in Mycobacterium tuberculosis

Objective To evaluate the accuracy of pyrosequencing for the mutation detection of katG gene in isoniazid resistance in Mycobacterium tuberculosis using Meta-analysis. Methods Searching PubMed,Web of Science,Elsevier,and China National Knowledge Infrastructure (CNKI),Weipu and WANFANG DATA to obtain the relevant English and Chinese-language articles,respectively.A written protocol and explicit study selection criteria was followed.Quality of included trials was assessed by QUADAS (quality assessment of diagnostic accuracy studies).Subsequently,the characteristics of the included articles were appraised and extracted.Heterogeneity of the included articles was tested by using STATA 10.0,which was used to select proper effect model.The fixed effects model was adopted using Meta-Disc software.Finally,sensitivity analysis was performed. Results Totally 114 research papers were collected and 9 articles were selected.The accordance between pyrosequencing and conventional sequencing result was 100%.Eight studies were involved including 945 specimens when katG gene was detected.The overall sensitivity and specificity were 0.77 (0.73,0.80) and 1.00 (0.99,1.00),respectively.The area under the SROC was 0.9882.As inhA gene was detected,the overall sensitivity and specificity were 0.19 (0.15,0.24) and 1.00 (0.98,1.00).The test was stable. Conclusions Our meta-analysis reveals that pyrosequencing is a highly specific tool for detection mutation of katG gene of isoniazid resistance.This result suggests that it is useful for screening of isoniazid resistance in diagnostic test.(Chin J Lab Med,2013,36:329-332) Key words: Sequence analysis; DNA; Mycobacterium tuberculosis; Isoniazid; Drug resistance; bacterial; Meta-analysis